Baseline Serum b-carotene Concentration and Mortality among Long-Term Asbestos-Exposed Insulators

Background: Although interventional trials demonstrated that moderate-dose b-carotene supplementation increases lung cancer mortality in smokers and asbestos-exposedworkers, differences in serum concentrations in absence of supplementation have not been studied in asbestos-exposed workers. Methods: A mortality analysis was performed to assess the relationship of nonsupplemented serum b-carotene to all-cause and cancer mortalities using 1981 to 1983 serum b-carotene concentration measurements from 2,646 U.S. white male insulators (mean age, 57.7 years). Multivariable-adjusted Cox proportional hazard models that included terms for age, duration of asbestos exposure, smoking, season, and region were fitted to estimatemortality HRs and 95% confidence intervals (CI) according to serum b-carotene concentrations. Results: Median follow-up was 12.8 years and 984 (33.8%) subjects died during the follow-up period, including 415 deaths from overall cancer and 219 deaths from lung cancer. The overall mortality HR for a serum b-carotene increase of 10 mg/dL was 0.97 (95% CI, 0.96–0.99). Compared with the lowest quartile, HRs were 0.90 (95% CI, 0.76–1.07) for the second (38–65 mg/dL), 0.80 (95% CI, 0.67–0.96) for the third (66–104 mg/dL), and 0.63 (95% CI, 0.51–0.77) for the highest serum b-carotene quartile ( 105 mg/dL). There was no association between serum b-carotene and overall cancer mortality (HR, 1.00; 95% CI, 0.97–1.02) or lung cancer mortality (HR, 0.99; 95% CI, 0.96–1.02). Conclusions:Higher nonsupplemented serum b-carotene concentrations were negatively associated with all-cause mortality among asbestos-exposed individuals. Impact: Serum b-carotene can be a marker of one or more determinants of reduced mortality in asbestos-exposed workers. Cancer Epidemiol Biomarkers Prev; 24(3); 555–60. 2014 AACR.